What kind of sewer receives waste water from a relatively small area and discharges into a sub-main sewer?

• A. Sub-main
• B. Main sewer
• C. Interceptor
• D. Branch sewer

Answer: (D)

Branch sewers collect wastewater from a relatively small area, such as a few streets or a single block, and discharge into a sub-main. This setup is what allows local areas to feed into a larger conduit that carries the combined flow toward the main sewer. In the hierarchy, a sub-main then receives from several branches and feeds the main sewer, the main sewer collects from sub-mains and transports toward the treatment system, and an interceptor is the largest line that carries wastewater over long distances to treatment. Because the scenario specifies a line serving a small area that feeds into a sub-main, the branch sewer is the best fit.